A method of and an apparatus for controlling a power of a light emitter in an optical disc drive to stabilize a servo control operation by efficiently compensating a slow tail effect occurring in a photodiode monitoring outputs of the light emitter are provided. The method includes: detecting an intensity of a laser signal reflected from a recording medium; normalizing the reference value using the detected value; and adjusting the reference value using the normalization result.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of controlling a power of a light emitter to stabilize an output level of the light emitter by comparing a reference value and a sampling output value of a photodiode monitoring the output of the light emitter and by controlling the output of the light emitter according to the comparison result, comprising: detecting an intensity of a laser signal reflected from a recording medium; normalizing the reference value using the detected intensity; and adjusting the reference value using the normalization result.
2. The method of claim 1 , wherein the reference value is usable to set a read level of the laser diode, and the intensity of the laser signal is detected in a read section of the laser signal.
3. The method of claim 1 , wherein the light emitter is a laser diode.
4. The method of claim 2 , wherein an intensity of a laser signal is obtained by sampling outputs of a main optical detector receiving a main beam output from the light emitter.
5. The method of claim 2 , wherein the intensity of the laser signal is obtained by sampling outputs of a sub optical detector receiving a sub beam output from the light emitter.
6. The method of claim 1 , wherein the reference value is normalized by using the detected intensity.
7. The method of claim 6 , wherein the reference value is divided by the detected intensity in the normalizing of the reference value.
8. The method of claim 1 , wherein the laser signal is one of sum signal and a push pull signal.
9. The method of claim 1 , wherein the laser signal is generated from one of a main beam and a side beam.
10. The method of claim 1 , wherein the read time of the laser signal is detectable by sampling the reproduction signal and low pass filtering the sampled value.
11. The method of claim 6 , further comprising adding an adaptive adjustment to the reference value according to lengths of one of marks and spaces on the recording medium.
12. An apparatus for controlling a power of a light emitter to stabilize an output level of the laser diode by comparing a reference value and a sampling output value of a photodiode monitoring the output of the laser diode and by controlling the output of the laser diode according to the comparison result, comprising: a sample and hold device which detects an intensity of a laser signal reflected from a recording medium; a normalizer which normalizes the reference value using the value sampled by the sample and hold device; and a controller which adjusts the reference value using an output of the normalizer.
13. The apparatus of claim 12 , wherein the light emitter is a laser diode.
14. The apparatus of claim 12 , wherein the reference value is usable to set a read level of the laser diode, and the sample and hold device performs sampling in a read section of the light emitter.
15. The apparatus of claim 12 , further comprising a low pass filter between the sample and hold device and the normalizer and performs low pass filtering of an output of the sample and hold device.
16. The apparatus of claim 12 , further comprising a switch which selects one of an output of a main optical detector receiving a main beam output from the light emitter and an output of a sub optical detector receiving a sub beam output from the light emitter and which outputs the selected one to the sample and hold device.
17. The apparatus of claim 12 , wherein the switch selects and outputs the output of the main optical detector when the recording medium is of an organic-color-type medium and outputs the output of the sub optical detector when the recording medium is of a phase-change-type recording medium.
18. The apparatus of claim 12 , further comprising a recording media type detector which detects a type of the recording medium installed in the apparatus.
19. The apparatus of claim 12 , wherein the normalizer is a divider that divides the reference value by an output of the sample and hold device.
20. The apparatus of claim 12 , wherein the controller adjusts the reference value at a recording speed where a recording frequency is near a slew rate frequency of the photodiode.
21. The apparatus of claim 12 , wherein the slew rate of the photodiode is specified.
22. The apparatus of claim 12 , further comprising a media checker which checks the type of the disc.
23. The apparatus of claim 22 , wherein the media checker checks after the disc is installed.
24. A computer-readable storage medium encoded with processing instructions for causing a computer to perform a method of controlling a power of a light emitter to stabilize an output level of the light emitter by comparing a reference value and a sampling output value of a photodiode monitoring the output of the light emitter and by controlling the output of the light emitter according to the comparison result, comprising: detecting an intensity of a laser signal reflected from a disc; normalizing the reference value using the detected intensity; and adjusting the reference value using the normalization result.
25. A method of removing the influence of a slow tail effect, comprising: comparing a read level of a laser signal controlled by an automatic power controller and a reference value for controlling the read level; and changing the reference value according to a result of the comparing, wherein the automatic power controller controls the read level such that the slow tail effect does not occur by: detecting a deviation between an ideal front monitor photodiode (FPD) signal resulting from the laser signal and an actual FPD signal resulting from the laser signal being incident on the FPD; and using a value of the detected deviation in the changing.
26. The method of claim 25 , further comprising: normalizing the reference value using the read value; and changing the reference value using the normalized reference value.
27. The method of claim 26 , wherein, when the slow tail effect occurs, the automatic power controller controls the read level of the laser signal according to the changed reference value so that the read level of the laser signal becomes stable.
28. The method of claim 25 , wherein an optical sensor detects the read level.
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June 3, 2004
December 4, 2007
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